Data networks have evolved from being single purpose providers of data-centric services such as file transfers and electronic mail, into multiservice platforms that provide traditional data services, voice communications services, and multimedia communication services. As the range of services has expanded, the requirements for data networks have also expanded to accommodate the unique characteristics of the different service types. For example, while file transfers may accommodate variable data rate transmission across the data network, voice communications services may require the allocation of resources within the network to enable constant data rate transmission. In addition, voice communication services may specify a maximum time delay, or latency, between the transmission of one packet, and the transmission of the succeeding packet. While some multimedia communications services may accommodate variable data rate transmission, they typically require the allocation of resources within the network to enable a targeted minimum data transmission rate.
Given that data networks do not have infinite bandwidth, multiservice data networks may be required to provide mechanisms for prioritizing the allocation of network resources among a diverse set of communication services. On such mechanism classifies data traffic carried within a network based on a class of service (CoS). CoS enables data traffic to be classified as belonging to one of a plurality of classes, wherein a class is typically defined according to a traffic profile. For example, one CoS may be characterized by a constant bit rate (CBR) traffic profile, where the quantitative constant data transfer rate may be a part of the traffic profile. In some conventional networks, the constant data transfer rate may be specified in bits/second. For CBR traffic, the network may attempt to allocate resources to enable traffic to be transmitted at the specified constant transfer rate. The CBR CoS may be suitable for voice communication traffic.
Another CoS may be characterized by a variable bit rate traffic (VBR) traffic profile, where a quantitative minimum data transfer rate, maximum data transfer rate, and/or burst time may be parts of the traffic profile. In some conventional networks, the minimum and maximum data transfer rates may be specified in bits/second, while the burst time may be specified in seconds. For VBR traffic, the network may attempt to allocate resources to enable traffic to be transmitted at the minimum data transfer rate for a sustained period of time, while enabling traffic to be transmitted at rates between the minimum data transfer rate and the maximum data transfer rate for a period of time, which is at least as long as is specified by the burst time traffic profile parameter. The VBR CoS may be suitable for video communication traffic.
Another CoS may be characterized by an unspecified bit rate (UBR) traffic profile. For UBR traffic, the network may not allocate resource and will transmit such traffic when there are available resources within the network. This is sometimes also referred to as “best effort” delivery of traffic. The UBR CoS may be suitable for file transfers and other traditional data-centric traffic.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.